1. Field of the Invention
The present invention relates to an image scanning and printing device, and more specifically to an image scanning and printing device which prints an image onto two sheets of recording papers or more in one printing process.
2. Description of Related Art
A conventional electro-photographic typed image scanning and printing device, which prints out a color image by a 4-cycle method, uses toner of four colors, blacK (K), Cyan (C), Magenta (M) and Yellow (Y). One cycle which begins with a development of an image based on color data of each of the colors and ends with a transfer of the image onto a transfer medium, is executed respectively on the color data of each of the colors. Then, by overlapping the images one on the other on the transfer medium, the formed color image is collectively transferred onto a recording paper. Under the printing process of the color image by the 4-cycle method, the image is formed on the transfer medium for each of the four colors KCMY, and then, the color image is printed onto a recording paper. As a result, the printing process of the color image required a printing time that is approximately four times longer than a printing time of a printing process of a monochrome image. Thus, there are problems that a longer period of time is required for printing when printing a color image onto multiple sheets of recording paper.
On the contrary, there is a printing device which can carry out a two-up printing process to print an image onto each of two sheets of recording papers that are supplied continuously in one printing process, like when printing onto one sheet of recording paper, in case it is instructed to print the image onto multiple sheets of recording papers of a prescribed size or smaller. For image data of unprocessed two pages that are received oldest by a data receiving unit, the printing device determines whether each image data is color data or monochrome data. Then, as shown in FIG. 6A and FIG. 6B, in case of a type number 0 in which both data are monochrome data, the image of only the K component is formed on the transfer medium, and the image is printed by a one-up monochrome printing process. In case of type numbers 1 through 3 in which the image data includes color data, the image is printed by a two-up color printing process. Further, in the one-up monochrome printing process of the type number 0, since a second sheet of the recording paper is supplied during the printing process of the image of the first page, the image of the second page is printed immediately after the first page is printed.
Therefore, when the image data of the two pages are both color data, by carrying out the two-up color printing process, the image can be printed within approximately half the time required by the one-up color printing process where the image of each page is printed one page at a time. Moreover, when the image data of the two pages are color data and monochrome data, the image can be printed in a shorter period of time than when printing by the type numbers 1 and 2 in which the image is printed by the one-up color printing process and the one-up monochrome printing process.
In the above-described printing device, it is determined and controlled whether or not to carry out the two-up color printing process based on the image data of the unprocessed two pages that are received by the data receiving unit. Therefore, it cannot be determined whether or not a two-up color printing process can be carried out until the image data of the original document is read into the data receiving unit when carrying out a printing process or the like.